The present invention relates to water-soluble transition metal complexes of the formula (I) 
where
G is xe2x80x94(CRb2)rxe2x80x94, xe2x80x94(CRb2)sxe2x80x94Si(Ra)2xe2x80x94(CRb2)txe2x80x94, xe2x80x94Axe2x80x2xe2x80x94Oxe2x80x94Bxe2x80x2xe2x80x94 or xe2x80x94Axe2x80x2xe2x80x94Z (R5) xe2x80x94Bxe2x80x2xe2x80x94,
R5 is hydrogen or is C1- to C28-alkyl, C3- to C14-cycloalkyl, C6- to C15-aryl, alkylaryl where the alkyl radical is of 1 to 20 carbon atoms and the aryl radical is of 6 to 15 carbon atoms, each of which is unsubstituted or substituted by functional groups based on elements of groups IVA, VA, VIA or VIIA of the Periodic Table of the Elements, or is N(Rb)2,
xe2x80x94Si(Rc)3 or a radical of the formula (II) 
where
q is an integer from 0 to 20 and the further substituents in (II) have the same meanings as in (I),
Axe2x80x2 and Bxe2x80x2 are each xe2x80x94(CRb2)rxe2x80x2,xe2x80x94 or xe2x80x94(CRb2)sxe2x80x94Si(Ra)2xe2x80x94(CRb2)txe2x80x94 or xe2x80x94N(Rb)xe2x80x94, an rxe2x80x2-, s- or t-atom component of a ring system or, together with Z, an (rxe2x80x2+1)-, (s+1)- or (t+1)-atom component of a heterocyclic structure,
Ra, independently of one another, are each C1- to C20-alkyl, C3- to C10-cycloalkyl, C6- to C15-aryl or alkylaryl where the alkyl moiety is of 1 to 10 carbon atoms and the aryl moiety is of 6 to 15 carbon atoms,
Rbis the same as Ra, or hydrogen or Si(Rc)3,
Rc is C1- to C20-alkyl, C3- to C10-cycloalkyl, C6- to C15-aryl or alkylaryl where the alkyl moiety is of 1 to 10 carbon atoms and the aryl moiety is of 6 to 15 carbon atoms,
r is 1, 2, 3 or 4,
r is 1 or 2,
s and t are each 0, 1 or 2, where 1xe2x89xa6s+txe2x89xa63,
z is a nonmetallic element from group VA of the Periodic Table of Elements,
M is a metal selected from the groups VIIIB, IB or IIB of the Periodic Table of Elements,
E1 and E2 are each a nonmetallic element from group VA of the Periodic Table of Elements,
R1 to R4 are each linear or branched C2- to C28-alkyl, C3- to C14-cycloalkyl or alkylaryl where the alkyl moiety is of 1 to 28 carbon atoms and the aryl moiety is of 6 to 15 carbon atoms, each of which is substituted by at least one polar protic or ionic functional group based on nonmetallic elements of groups IVA to VIA of the Periodic Table of Elements,
L1 and L2 are formally charged or neutral ligands,
X are formally monovalent or polyvalent anions,
p is 0, 1, 2, 3 or 4,
m and n are each 0, 1, 2, 3 or 4
and p =mxc3x97n.
The present invention furthermore relates to the use of these metal complexes for the preparation of linear, alternating copolymers of carbon monoxide and xcex1-olefinically unsaturated compounds. The present invention also relates to water-soluble chelate ligands, a process for the preparation of these chelate ligands and their use for the preparation of water-soluble transition metal complexes.
Transition metal-catalyzed processes for the preparation of linear, alternating copolymers of carbon monoxide and xcex1-olefinically unsaturated compounds, also referred to as carbon monoxide copolymers or polyketones for short, are known. For example, in EP-A 0 121 965 a cis-palladium complex chelated with bidentate phosphine ligands, [Pd(Ph2P(CH2)3PPh2)] (OAc)2 (Ph=phenyl, Ac=acetyl), is used. The carbon monoxide copolymerization can be carried out in suspension, as described in EP-A 0 305 011, or in the gas phase, for example according to EP-A 0 702 045. Frequently used suspension media are on the one hand low molecular weight alcohols, in particular methanol (cf. also EP-A 0 428 228), and on the other hand nonpolar or polar aprotic liquids such as dichloromethane, toluene or tetrahydrofuran (cf. EP-A 0 460 743 and EP-A 0 590 942). Complex compounds having bisphosphine chelate ligands whose radicals on the phosphorus atom are aryl or substituted aryl groups have proven particularly suitable for said polymerization process. Accordingly, 1,3-bis(diphenylphosphino)propane or 1,3-bis[di-(o-methoxyphenyl)phosphino]propane is particularly frequently used as a chelate ligand (cf. also Drent et al., Chem. Rev. 96 (1996), 663-681). Usually, the carbon monoxide copolymerization is carried out in the presence of acids.
The carbon monoxide copolymerization in low molecular weight alcohols, such as methanol, has the disadvantage that the resulting carbon monoxide copolymer absorbs up to 80% by volume of, for example, methanol. Accordingly, a large amount of energy is required to dry the resulting carbon monoxide copolymer and to isolate it in pure form. Another disadvantage is that, even after an intensive drying process, residual amounts of alcohol still remain in the carbon monoxide copolymer. Molding materials prepared in this manner are thus from the outset unsuitable for use as packaging materials for food. EP-A 0 485 035 proposes the use of additions of water in amounts of from 2.5 to 15% by weight to the alcoholic suspending medium in order to eliminate the residual amounts of low molecular alcohol in the carbon monoxide copolymer. However, this procedure, too, does not lead to methanol-free copolymers. On the other hand, the use of halogenated hydrocarbons or aromatics, such as dichloromethane or chlorobenzene or toluene, gives rise to problems particularly in disposal.
To overcome the disadvantages associated with said suspending media, Jiang and Sen, Macromolecules 27 (1994), 7215-7216, describe the preparation of linear, alternating carbon monoxide copolymers in aqueous systems using a catalyst system consisting of [Pd(CH3CN4) ] (BF4)2 and 1,3-bis[di(3-sulfophenyl)phosphino]propane as water-soluble chelate ligands. However, the catalyst activity achieved is very low and therefore unsuitable for a large-scale industrial preparation.
Compared with Jiang and Sen, Verspui et al., Chem. Commun. (1998), 401-402, achieve an increase in the catalyst activity in the copolymerization of carbon monoxide and ethene by using said chelate ligands in substantially purer form as a result of an improved synthesis method (cf. also Hermann et al., Angew. Chem. Int. Ed. Engl. 34 (1995) 811 et seq.). Furthermore, the presence of a Brxc3x6nsted acid is required in order to obtain catalyst activities improved in comparison with Jiang and Sen. Although it is actually possible to prepare the chelate ligand 1,3-bis[di(3-sulfophenyl)phosphino]propane in purer form with the aid of an improved synthesis method, this does not provide a route to suitable chelate ligands having other substitution patterns. Thus, the water-soluble transition metal complexes described are limited exclusively to sulfonated aromatic substituents on phosphorus. Preparation of these chelate ligands furthermore requires the handling of very aggressive substances, such as boric acid, concentrated sulfuric acid and oleum. Owing to the given structure, an extension to other systems is in principle not possible.
It is therefore desirable, for the copolymerization of carbon monoxide and xcex1-olefinically unsaturated compounds in aqueous systems, to be able to rely on metal complexes which should from the outset permit a large number of different substituents on chelate ligands and at the same time enable constantly good reproducibility in combination with high efficiency.
It is an object of the present invention to provide water-soluble transition metal complexes which are suitable as the active component of a catalyst system for the preparation of linear, alternating carbon monoxide copolymers in aqueous media.
We have found that this object is achieved by the water-soluble transition metal complexes defined at the outset. We have also found a process for the preparation of these transition metal complexes and their use for the preparation of linear, alternating carbon monoxide copolymers.
We have furthermore found water-soluble chelate ligands, a process for the preparation of these chelate ligands and their use for the preparation of water-soluble transition metal complexes.
Preferred novel water-soluble transition metal complexes are based on compounds of the formula (Ia) 
where
G is xe2x80x94(CRb2)rxe2x80x94 or xe2x80x94(CRb2)xe2x80x94N(R5)xe2x80x94(CRb2)xe2x80x94, where
Rb is hydrogen, C1- to C10-alkyl or C6- to C10-aryl,
r is 1, 2, 3 or 4,
R5 is hydrogen, C1- to C10-alkyl, C3- to C10-cycloalkyl, C6- to C15-aryl or C1- to C10-alkyl, C3- to C10-cycloalkyl or C6- to C5-aryl, which is substituted by functional groups based on elements of groups IVA, VA, VIA and VIIA of the Periodic Table of Elements,
m is palladium or nickel,
E1 and E2 are each phosphorus,
R1 to R4 are linear, branched or carbocycle-containing C2- to C28-alkyl units or C3- to C14-cycloalkyl units which have at least one terminal or internal hydroxyl, amino acid, carboxyl, phosphoric acid, ammonium or sulfonic acid group, or alkylaryl where the alkyl moiety is of 1 to 20 carbon atoms and the aryl moiety is of 6 to 15 carbon atoms, the alkyl or aryl moiety being substituted by at least one hydroxyl, carboxyl, amino acid, phosphoric acid, ammonium or sulfonic acid group,
L1 and L2 are each acetate, trifluoroacetate, tosylate or halide, and
p, m, n are each 0.
In principle, bidentate chelate ligands of the formula (R1) (R2) E1xe2x80x94Gxe2x80x94E2 (R3) (R4) (III), in which the substituents and indices have the abovementioned meanings, are suitable as a component of the transition metal complex (I).
The bridging structural unit G in the novel metal complexes (I) or the chelate ligand (III) consists in general of monoatomic or polyatomic linking segments. A bridging structural unit is understood in principle as meaning a group which links the elements E1 and E2 to one another. Such structural units include, for example, substituted or unsubstituted alkylene chains or those alkylene chains in which an alkylene unit is replaced by a silylene group, amino, phosphino or an ether oxygen.
The preferred monoatomically bridged structural units are those having a bridging atom from group IVA of the Periodic Table of Elements, such as xe2x80x94C(Rb)2xe2x80x94 or xe2x80x94Si(Ra)2xe2x80x94, where Ra, independently of one another, are in particular each linear or branched C1- to C10-alkyl, for example methyl, ethyl, i-propyl or t-butyl, C3- to C6-cycloalkyl, such as cyclopropyl or cyclohexyl, C6 to C10-aryl, such as phenyl or naphthyl, C6- to C10-aryl substituted by functional groups based on nonmetallic elements of groups IVA, VA, VIA or VIIA of the Periodic Table, for example tolyl, (trifluoromethyl)phenyl, dimethylaminophenyl, p-methoxyphenyl or partially halogenated or perhalogenated phenyl, aralkyl where the alkyl moiety is of 1 to 6 carbon atoms and the aryl moiety is of 6 to 10 carbon atoms, for example benzyl, and Rb are in particular each hydrogen and may furthermore have the meanings stated above for Ra. Ra is in particular methyl and Rb is in particular hydrogen.
Among the polyatomically bridged systems, t he diatomically, triatomically and tetraatomically bridged structural units are noteworthy, the triatomically bridged systems generally being preferably used.
Suitable triatomically bridged structural units are based in general on a chain of carbon atoms, for example propylene (xe2x80x94CH2CH2CH2xe2x80x94), or on a bridge unit having a heteroatom from group IVA, VA or VIA of the Periodic Table of Elements, such as silicon, nitrogen, phosphorus or oxygen, in the chain skeleton.
The bridge carbon atoms may be substituted in general by C1- to C6-alkyl, such as methyl, ethyl or t-butyl, by C6- to C10-aryl such as phenyl or by functional groups based on elements of groups IVA, VA, VIA or VIIA of the Periodic Table of Elements, for example triorganosilyl, dialkylamino, alkoxy, hydroxyl or halogen. Suitable substituted propylene bridges are, for example, those having a methyl, phenyl, hydroxyl, trifluoromethyl, co-hydroxyalkyl or methoxy group in the 2 position.
Among the polyatomically bridged structural units having a heteroatom in the chain skeleton, advantageously used compounds are those in which Z is nitrogen or phosphorus, in particular nitrogen (cf. also formula (I)). R5 on Z may be in particular hydrogen, linear or branched C1- to C28-alkyl, such as methyl, ethyl, isopropyl, tert-butyl, n-hexyl or n-dodecyl, C3- to C14-cycloalkyl, in particular C3- to C8-cycloalkyl, such as cyclopropyl or cyclohexyl, C6- to C15-aryl, in particular C6- to C10-aryl, for example phenyl, or alkylaryl where the alkyl radical is of 1 to 20 carbon atoms and the aryl radical is of 6 to 10 carbon atoms, for example benzyl.
Said alkyl and aryl radicals include both unsubstituted and substituted compounds. The substituted compounds may be, for example, functional groups based on elements of groups IVA, VA, VIA or VITA of the Periodic Table of Elements. Inter alia, triorganosilyl groups, such as trimethylsilyl or tert-butyldiphenylsilyl, the carboxyl group or carboxylic acid derivatives, such as esters or amides, primary, secondary or tertiary amino, such as dimethylamino or methylphenylamino, the nitro and the hydroxyl group and furthermore alkoxy, methoxy or ethoxy, the sulfonate group and halogen, such as fluorine, chlorine or bromine, are suitable. For the purposes of the present invention aryl includes substituted and unsubstituted hetaryl, for example pyridyl or pyrrolyl. Alkyl radicals R5 also include long-chain alkylene having 12 to 22 carbon atoms in the chain, which may have polar protic or ionic functional groups, such as the sulfo, carboxyl, hydroxyl, amino acid or ammonium group, for example in a terminal position.
Preferred radicals R5 include those compounds which constitute an electron-attracting substituent. Suitable electron-attracting substituents are, for example, alkyl groups having one or more electron-attracting radicals, such as fluorine, chlorine, nitrile or nitro xcex1 or xcex2 to Z. Aryl groups having said electron-attracting radicals and, as radicals bonded directly to Z, also the nitrile, sulfonate and nitro group are furthermore suitable. Examples of suitable electron-attracting alkyl radicals are trifluoromethyl, trichloroethyl, difluoromethyl, 2,2,2-trifluoroethyl, nitromethyl and cyanomethyl. Examples of suitable electron-attracting aryl radicals are m-, p- and o-fluoro- and chlorophenyl, 2,4-difluorophenyl, 2,4-dichlorophenyl, 2,4,6-trifluorophenyl, 3,5-bis(trifluoromethyl)phenyl, nitrophenyl, 2-chloro-5-nitrophenyl and 2-bromo-5-nitrophenyl. In this context, carbonyl units are also suitable radicals R5, so that, if Z is nitrogen, Z and R5 form a carboxamide functional group. A suitable radical of this type is acetyl or trifluoroacetyl.
R5 is particularly preferably tert-butyl, phenyl, p-trifluorophenyl, trifluoromethyl, 2,2,2-trifluoroethyl, pentafluorophenyl, 3,5-bis(trifluoromethyl)phenyl or ortho-difluorophenyl, e.g. 3,4-difluorophenyl, meta-difluorophenyl, e.g. 2,4-difluorophenyl, or para-difluorophenyl, e.g. 2,5-difluorophenyl.
Suitable units Axe2x80x2 and Bxe2x80x2 according to the formulae (I) to (III) are C1- to C4-alkylene units in substituted or unsubstituted form, for example methylene, ethylene, propylene or ethylidene, propylidene and benzylidene. Methylene, ethylene, ethylidene and benzylidene are preferred, methylene being particularly preferably used.
Axe2x80x2 and Bxe2x80x2 may also be a monoatomic, diatomic or triatomic or tetraatomic component of an aliphatic or aromatic ring system. For example, Axe2x80x2 and Bxe2x80x2 may be a methylene or ethylene unit of a cyclopropyl, cyclopentyl or cyclohexyl ring. Aliphatic and aromatic heterocyclic structures are also suitable ring systems.
Axe2x80x2 and Bxe2x80x2 may furthermore be part of a heterocyclic structure which is formed from the components Axe2x80x2xe2x80x94Zxe2x80x94R5 and Bxe2x80x2xe2x80x94Zxe2x80x94R5, i.e. Axe2x80x2xe2x80x94Zxe2x80x94R5 and Bxe2x80x2xe2x80x94Zxe2x80x94R5 may form, for example, a substituted or unsubstituted pyrrolidine or piperidine ring.
Suitable chelating atoms E1 and E2 are, independently of one another, the nonmetallic elements of group VA of the Periodic Table of Elements, nitrogen and phosphorus being preferably used, in particular phosphorus. In a preferred embodiment, E1 and E2 in the compounds (I) and (III) are each phosphorus.
In the novel transition metal complexes, R1 to R4 are each C2- to C20-alkyl, C3- to C14-cycloalkyl, preferably C3- to C8-cycloalkyl, or alkylaryl where the alkyl moiety is of 1 to 28 carbon atoms and the aryl moiety is of 6 to 15 carbon atoms, each of which is substituted by at least one polar protic or ionic functional group based on elements of groups IVA to VIA of the Periodic Table of Elements. R1 to R4 are preferably linear, branched or carbocycle-containing C2- to C28-alkyl or C3- to C14-cycloalkyl units which have at least one terminal or internal hydroxyl, carboxyl, phosphoric acid, ammonium, amino acid or sulfonic acid group, or are alkylaryl where the alkyl moiety is of 1 to 28 carbon atoms and the aryl moiety is of 6 to 15 carbon atoms, the alkyl or aryl moiety is substituted by at least one hydroxyl, carboxyl, phosphoric acid, ammonium, amino acid or sulfonic acid group.
The salts of the carboxylic acids, phosphoric acids, amino acids or sulfonic acids may also be used. Suitable salts are, for example, alkali metal or alkaline earth metal salts, such as sodium, potassium or magnesium carboxylates or sulfonates. Suitable alkyl radicals R1 to R4 are, for example, alkylene units having one or two terminal hydroxyl, carboxyl, sulfo or ammonium groups. R1 to R4 may also have more than two polar groups, for example four or six hydroxyl, ammonium or carboxyl groups. Accordingly, R1 to R4 in a chelate compound (III) may each also have different functional groups. Furthermore, R1 to R4 may have functional groups in numbers differing from one another. Suitable radicals R1 to R4 are accordingly compounds of the formula (IV)
xe2x80x83xe2x80x94(CRd2)kxe2x80x94(T)1xe2x80x94(CRd2)kxe2x80x2,xe2x80x94Yxe2x80x83xe2x80x83(IV),
where
Rd is the same as Rb, or Y,
T is C3- to C10-cycloalkylene, in particular C3- to C6-cycloalkylene, or C6- to C15-arylene, in particular C6- to C10-arylene, unsubstituted or substituted by Rdor Y,
k is from 0 to 20 if 1 is 0 or 1 is 1 and T is cycloalkyl and is from 1 to 20 if 1 is 1 and T is aryl,
kxe2x80x2 is from 0 to 20,
l is 0 or 1 and
Y is a polar protic or ionic functional group based on elements of groups IVA to VIA of the Periodic Table of Elements.
Suitable radicals Y are the hydroxyl, amino acid, carboxyl, phosphoric acid, ammonium and sulfonic acid group. Preferred cycloaliphatic radicals T are cyclopropyl and cyclohexyl and a preferred aryl or arylene unit T is phenyl(ene). k is preferably from 2 to 20, especially from 3 to 18, and kxe2x80x2 is preferably from 0 to 10, in particular from 1 to 8.
The novel water-soluble chelate ligands of the formula (III) (R1) (R2)E1xe2x80x94Gxe2x80x94E2(R3) (R4) are obtained, for example,
a) by converting a compound of the formula (IIIa)
Lxe2x80x94(CRb2)rxe2x80x94L or Lxe2x80x94(CRb2)xe2x80x94N(R5)xe2x80x94(CRb2)xe2x80x94Lxe2x80x83xe2x80x83(IIIa),
where
Rb is hydrogen, C1- to C10-alkyl or C6- to C10-aryl,
r is 1, 2, 3 or 4,
R5 is hydrogen, C1- to C10-alkyl, C3- to C10-cycloalkyl, C6- to C15-aryl or C1- to C10-alkyl, C3- to C10-cycloalkyl or C6- to C15-aryl substituted by functional groups based on the elements of groups IVA, VA, VIA and VIIA of the Periodic Table of Elements and
L, independently of one another, are each chloride, bromide or iodide, by means of an Arbuzov reaction with a trialkoxyphosphine into a compound of the formula (IIIb) where
L is P(Lxe2x80x2)3 and
Lxe2x80x2 is Oxe2x80x94C1- to Oxe2x80x94C6-alkyl, Oxe2x80x94C6- to Oxe2x80x94C10-aryl or Oxe2x80x94alkylaryl where the alkyl moiety is of 1 to 6 carbon atoms and the aryl moiety is of 6 to 20 carbon atoms,
b) reducing the compound (IIIb) to the compound of the formula (IIIc), where Lxe2x80x2 is hydrogen, and
c) subjecting the compound of the formula (IIIc) to free radical polymerization in the presence of at least four equivalents of an olefinically unsaturated compound which has at least one polar protic or ionic functional group based on nonmetallic elements of groups IVA to VIA of the Periodic Table of Elements.
It is preferable to use an olefinically unsaturated compound of the formula (IVa)
CH2xe2x95x90C(Rd)xe2x80x94(CRd2)kxe2x88x921xe2x80x94(T)1xe2x80x94(CRd2)kxe2x80x2,xe2x80x94Yxe2x80x83xe2x80x83(IVa)
where
Rd, independently of one another, are each hydrogen, C1- to C20-alkyl, C3- to C10-cycloalkyl, C6- to C15-aryl or alkylaryl where the alkyl moiety is of 1 to 10 carbon atoms and the aryl moiety is of 6 to 15 carbon atoms, and may additionally be Y,
T is C3- to C10-cycloalkylene, in particular C3- to C6-cycloalkylene, or C6- to C15-arylene, in particular C6- to C10-arylene, unsubstituted or substituted by Rd or Y,
k is from 1 to 20 if 1 is 0 or 1 is 1 and T is cycloalkyl and is from 2 to 20 if 1 is 1 and T is aryl,
kxe2x80x2 is from 0 to 20,
l is 0 or 1 and
Y is a polar protic or ionic functional group based on elements of groups IVA to VIA of the Periodic Table of Elements.
For the preparation of, for example, propylene-bridged (Gxe2x95x90xe2x80x94(CH2)3xe2x80x94) chelate ligand compounds (III), it is usual to start from commercially available 1,3-dibromopropane. A double Arbuzov reaction, for example with trimethoxy- or triethoxyphosphine, gives 1,3-bisphosphonic acid derivatives, which can be reduced, as described in Methoden der organischen Chemie (Houben-Weyl), 4th edition, Volume XII/1, part 1, Georg Thieme Verlag, 1963, page 62, to 1,3-diphosphinopropane. A suitable reducing agent is, for example, lithium aluminum hydride or diisobutylaluminum hydride. Via a hydrophosphination reaction with said functional olefins, 1,3-diphosphinopropane provides a flexible route to substituted bisphosphine chelate ligands. The hydrophosphination takes place in general via a free radical mechanism and can be initiated thermally or photochemically or with the aid of a free radical initiator. In general, temperatures of from 20 to 100xc2x0 C. and pressures of from 0.1 to 5 bar are required for thermal initiation. A suitable free radical initiator is, for example, di-tert-butyl peroxide or azobisisobutyronitrile. For the photochemical initiation, as a rule UV radiation from a high-pressure mercury lamp over a period of from 2 to 48 hours is sufficient for a quantitative hydrophosphination. The last-mentioned process is as a rule preferred. Processes involving free radical initiation generally give anti-Markovnikov products in the hydrophosphination.
Suitable chelate ligand compounds can also be prepared under conditions of acidic catalysis. Owing to the isomerization of the olefin double bond under the acidic reaction conditions, the products obtained by this process frequently occur as a mixture. The hydrophosphination step in the process is described, for example, in Methoden der organischen Chemie (Houben-Weyl), 4th edition, Volume XII/1, part 1, Georg Thieme Verlag, 1963, pages 25 to 28.
For the preparation of chelate ligands having the radicals R1 to R4 which carry carboxyl groups, it has proven advantageous to start from olefinically unsaturated compounds which have been derivatized with corresponding carboxylic ester groups and subsequently to use these in the hydrophosphination reaction. The free carboxylic acids can be obtained by hydrolysis by known methods.
According to the invention, all olefins which are covered by this class of compounds are suitable for said hydrophosphination reaction, provided that they have a polar protic or ionic functional group. For example, C3- to C28-alkenes having at least one internal or terminal double bond and at least one hydroxyl, amino acid, carboxyl, phosphoric acid, ammonium or sulfonic acid group are suitable. Olefinic compounds having aromatic radicals are also suitable, it being possible for the functional group to be both on the aliphatic and on the aromatic radical, for example 4- (1-pentenyl)benzoic acid or 3-phenyl-pent-5-enecarboxylic acid. Olefinic compounds having aliphatic carbocycles in the alkylene chain or as substituent are furthermore suitable. Moreover, cyclic olefins, such as cyclohexen-3-ol or cycloocten-4-ol, may also be used. It is of course also possible to use olefins having a plurality of polar protic or ionic functional groups. Suitable xcex1-olefinic compounds are preferably used in the hydrophosphination reaction of the xcex1,xcfx89-bisphosphines. Suitable compounds of this type are, for example, also heteroatom-containing xcex1-olefins, such as (meth)acrylates or (meth)acrylamides and homoallyl- or allyl alcohols.
Radicals R1 to R4 in which the hydrophilic character induced by the polar protic or ionic functional groups is sufficient to render the metal complex (I) completely water-soluble are particularly preferably used. The larger the number of functional groups on the radicals R1 to R4, the greater may also be the lipophilic aliphatic or aliphatic-aromatic fraction. For example, preferred radicals R1 to R4 each having a hydroxyl group are those having 2 to 15 carbon atoms in the alkyl unit.
In a particularly preferred embodiment of the chelate ligands (III), R1 to R4 as alkyl substituents with a hydroxyl group have 4 to 12, in particular 4 to 7, carbon atoms, R1 to R4 as alkyl substituents with a carboxyl group have 4 to 15, in particular 5 to 12, carbon atoms, R1 to R4 as alkyl substituents with a sulfonic acid group have 4 to 18, in particular 5 to 15, carbon atoms and R1 to R4 as alkyl substituents with an ammonium group have 4 to 22, in particular 5 to 20, carbon atoms.
Examples of suitable chelate ligands (III) are 1,3-bis(di-5-hydroxypentyl)phosphinopropane,
1,3-bis(di-6-hydroxyhexyl)phosphinopropane,
1,3-bis(di-7-hydroxyheptyl)phosphinopropane,
1,3-bis(di-8-hydroxyoctyl)phosphinopropane,
1,3-bis(di(3-hydroxycyclopentyl)propyl)phosphinopropane,
1,3-bis[di-5-sulfopentyl]phospinopropane,
1,3-bis[di-6-sulfohexyl]phosphinopropane,
1,3-bis[di-7-sulfoheptyl]phosphinopropane,
1,3-bis[di-8-sulfooctyl]phosphinopropane,
1,3-bis[di(3-sulfocyclopentyl)propyl]phosphinopropane,
1,3-bis(di-5-pentanoyl)phosphinopropane,
1,3-bis(di-6-hexanoyl)phosphinopropane,
1,3-bis(di-7-heptanoyl)phosphinopropane,
1,3-bis(di-8-octanoyl)phosphinopropane,
bis[(di-5-hydroxypentyl)phospinomethyl]phenylamine,
bis[(di-6-hydroxyhexyl)phosphinomethyl]phenylamine,
bis[(di-7-hydroxyheptyl)phosphinomethyl]phenylamine,
bis[(di-8-hydroxyoctyl)phosphinomethyl]phenylamine,
bis[(di(3-hydroxycyclopentyl)propyl]phenylamine,
bis[(di-5-sulfopentyl)phosphinomethyl]phenylamine,
bis[(di-6-sulfohexyl)phospinomethyl]phenylamine,
bis[(di-7-sulfoheptyl)phosphinomethyl]phenylamine,
bis[(di-8-sulfooctyl)phosphinomethyl]phenylamine,
bis[(di-3-sulfocyclopentyl) propyl]phospinomethyl]phenylamine,
bis[(di-5-pentanoylphospinomethyl]phenylamine,
bis[(di-6-hexanoyl)phospinomethyl]phenylamine,
bis[(di-7-heptanoyl)phosphinomethyl]phenylamine and
bis[(di-8-octanoyl)phosphinomethyl]phenylamine.
Particularly preferred among said chelate ligand compounds are those in which R1 to R4 are a hexyl, octyl, cyclopentyl or cyclohexyl radical substituted by a hydroxyl or carboxyl group.
Suitable metals M of the novel transition metal complexes are the metals of groups VIIIB, IB and IIB of the Periodic Table of Elements, i.e. chiefly the platinum metals, such as ruthenium, rhodium, osmium, iridium and platinum and very particularly preferably palladium, in addition to iron, cobalt and nickel. In the complexes (I), the metals may be formally uncharged, formally bearing a single positive charge or preferably formally bearing a double positive charge.
Suitable formally charged inorganic ligands L1 and L2 are hydride, halides, sulfates, phosphates or nitrates. Carboxylates or salts of organic sulfonic acids, such as methylsulfonate, trifluoromethylsulfonate or p-toluenesulfonate, are also suitable. Among the salts of organic sulfonic acids, p-toluenesulfonate is preferred. Preferred formally charged ligands L1 and L2 are carboxylates, preferably C1- to C20-carboxylates, in particular C1- to C7-carboxylates, e.g. acetate, trifluoroacetate, propionate, oxalate, citrate or benzoate. Acetate is particularly preferred.
Other suitable formally charged organic ligands L1 and L2 are aliphatic C1 to C20 radicals, cycloaliphatic C3 to C30 radicals, C7- to C20-aralkyl radicals having C6- to C14-aryl radicals and C1- to C6-alkyl radicals and aromatic C6- to C20 radicals, for example, methyl, ethyl, propyl, isopropyl, tert-butyl, n-pentyl, i-pentyl, cyclohexyl, benzyl, phenyl, and aliphatically or aromatically substitued phenyl radicals.
Suitable formally uncharged ligands L1 and L2 are in general Lewis bases, i.e. compounds having at least one free electron pair. Lewis bases whose free electron pair or free electron pairs is or are present on a nitrogen or oxygen atom are particularly suitable, for example nitriles, R-CN, ketones, ethers, alcohols or water. C1- to C10-nitriles, such as acetonitrile, propionitrile or benzonitrile, or C2- to C10-ketones, such as acetone or acetylacetone, or C2- to C10-ethers, such as dimethyl ether, diethyl ether or tetrahydrofuran, are preferably used. In particular, acetonitrile or tetrahydrofuran is used.
In principle, the ligands L1 and L2 may be present in any desired ligand combination, i.e. the metal complex (I) may, for example, contain a nitrate or an acetate radical, a p-toluenesulfonate and an acetate radical or a nitrate ligand or a formally charged organic ligand, such as tert-butyl. L1 and L2 are preferably present as identical ligands in the metal complexes.
Depending on the formal charge of the complex fragment containing the metal M, the metal complexes contain anions X. If the M-containing complex fragment is formally uncharged, however, the novel complex (I) contains no anion X. Advantageously used anions X are those which have very little nucleophilic character, i.e. very little tendency to form a chemical bond with the central metal M.
Suitable anions X are, for example, perchlorate, sulfate, phosphate, nitrate and carboxylates, for example acetate, trifluoroacetate, trichloroacetate, propionate, oxalate, citrate and benzoate, and conjugated anions of organosulfonic acids, for example methylsulfonate, trifluoromethylsulfonate and para-toluenesulfonate, and furthermore tetrafluoroborate, tetraphenylborate, tetrakis(pentafluorophenyl)borate, tetrakis[bis(3,5-trifluoromethyl)phenyl]borate, hexafluorophosphate, hexafluoroarsenate or hexafluoroantimonate. Perchlorate, trifluoroacetate, sulfonates, such as methylsulfonate, trifluoromethylsulfonate, p-toluenesulfonate, tetrakis[bis(3,5-trifluoromethyl)phenyl]borate, tetrafluoroborate or hexafluorophosphate are preferably used, in particular trifluoromethylsulfonate, trifluoroacetate, perchlorate or p-toluenesulfonate.
For example, suitable defined transition metal complexes are:
[1,3-bis(di-5-hydroxypentyl)phospinopropane]palladium(II) acetate,
[1,3-bis(di-6-hydroxyhexyl)phosphinopropane]palladium(II) acetate,
[1,3-bis(di(3-hydroxycyclopentyl)propyl)phosphinopropane]palladium(II) acetate,
[1,3-bis(di-8-hydroxyoctyl)phospinopropane]palladium(II) acetate and
[1,3-bis(di(3-hydroxycyclohexyl)propyl)phospinopropane]palladium (II) acetate.
The transition metal complexes described are soluble in water, at least in small amounts. As a rule, these metal complexes are readily to very readily soluble in water.
Defined transition metal complexes (I) can be prepared by the following processes.
The preparation is carried out for the neutral chelate complexes (p=0) by exchanging weakly coordinating ligands for example 1,5-cyclooctadiene, benzonitrile or tetramethylethylenediamine, which are bonded to the corresponding transition metal compounds, for example transition metal halides, transition metal (alkyl)(halides) or transition metal-diorganyls, for the novel chelate ligands of the formula (III) having the meanings described above.
The reaction is carried out in general in a polar solvent, for example acetonitrile, acetone, ethanol, diethyl ether, dichloromethane or tetrahydrofuran, or mixtures thereof at from xe2x88x9278 to +60xc2x0 C.
Furthermore, neutral metal complexes (I) in which L1 and L2 are carboxylate, e.g. acetate, can be prepared by reacting transition metal salts, for example Pd(OAc)2, with the chelate ligands (III) described in acetonitrile, acetone, ethanol, diethyl ether, dichloromethane, tetrahydrofuran or water at room temperature. Solvent mixtures may also be used.
Another suitable method of synthesis is the reaction of the chelate complexes of the formula (I) with organometallic compounds of groups IA, IIA, IVA and IIB, for example C1- to C6-alkyls of the metals lithium, aluminum, magnesium, tin or zinc, formally charged inorganic ligands L1 and L2 as defined above being exchanged for formally charged aliphatic, cycloaliphatic or aromatic ligands L1 and L2 as likewise defined above. The reaction is carried out in general in a solvent, for example diethyl ether or tetrahydrofuran, at from xe2x88x9278 to 65xc2x0 C.
Monocationic complexes of the formula (I) (p=1) can be obtained, for example, by reacting (chelate ligand)metal(acetate)(organo) or (chelate ligand)metal(halo)(organo) complexes with stoichiometric amounts of a metal salt Mxe2x80x2X. The reactions are carried out in general in coordinating solvents, for example acetonitrile, benzonitrile or tetrahydrofuran, at from xe2x88x9278 to 65xc2x0 C.
It is advantageous if the metal salts Mxe2x80x2X fulfil the following criteria. The metal Mxe2x80x2 should preferably form sparingly soluble metal chlorides, for example silver chloride. The salt anion should preferably be a nonnucleophilic anion X as defined above.
Suitable salts for the formation of the cationic complexes are silver tetrafluoroborate, silver hexafluorophosphate, silver trifluoromethanesulfonate, silver perchlorate, silver paratoluenesulfonate, silver trifluoroacetate and silver trichloroacetate.
The dicationic complexes (p=2) are prepared similarly to the monocationic complexes except that, instead of the (chelate ligand)metal(acetate)(organo) or the (chelate ligand)metal(halo)(organo) complexes, the (chelate ligand)metal (diacetate) or (chelate ligand)metal(dihalo) complexes are now used as the intermediates.
Another suitable process for the preparation of the dicationic complexes (I) is the reaction of [Q4M]X2 with the chelate ligands of the formula (III) which are defined at the outset. Here, Q are identical or different weak ligands, for example acetonitrile, benzonitrile or 1,5-cyclooctadiene, and M and X have the meanings defined above.
A preferred process for the preparation of the metal complexes of the formula (I) is the reaction of the dihalo-metal precursor complexes with silver salts containing noncoordinating anions.
The novel water-soluble transition metal complexes can be used as an essential component of a catalyst system for the copolymerization of carbon monoxide and xcex1-olefinically unsaturated compounds in particular in aqueous media. As a further constituent of the catalyst system, a Lewis or protic acid can be used as an activator component.
The novel water-soluble transition metal complexes have a constantly high average catalyst activity even after a reaction time of several hours.